Two part curable compositions are used in a variety of applications such as adhesives, coatings, foams and the like, where rapid cure is required for the application, especially where the two parts are not shelf stable when in contact with one another. Shelf stable means that the composition does not cure in storage. Two part curable compositions which exhibit high viscosities may be difficult to mix and apply. Examples of such systems are disclosed in WO 2012/151086 and WO 2012/151085, incorporated herein by reference in their entirety. This is especially a problem where the two parts are mixed in a relatively high volumetric ratio of one part to the other. When the two parts are mixed in high volumetric ratio of one part to the other, the two dissimilar parts may be stored in a bag in bag tube, wherein the smaller volumetric part is stored in a bag disposed in the higher volumetric part, one of the bags is generally disposed along the outer wall forming the tube. The bag forms a barrier to contact of the two parts. This configuration allows for utilizing any volumetric ratio without concern for the size of the material tubes and their ability to work with standard two-part mixers. Common concerns include high back pressure of the curable material and thorough mixing of the materials. If the back pressure resulting from introducing highly viscous materials into the mixer used is too high, the curable materials will not pass through the mixing chamber and cannot be applied. If the two parts are not adequately mixed the curable material will not cure in a manner desired. A complicating factor is that many two part composition are applied in remote locations or by consumers, where there is limited or no access to applicators capable of applying sufficiently high pressures to overcome the back pressures and thoroughly mix the parts. many common manually driven or battery driven applicators do not have the capability to overcome backpressures resulting from trying to pass a highly viscous material through mixers capable of properly mixing such compositions.
Complex mixing systems have been developed to address these problems, see for example, EP 1,189,686; EP 1,830,070 and EP 2,011,562 incorporated herein by reference in their entirety. Such systems can be complicated to use or costly to manufacture.
What is needed is mixer systems that can thoroughly mix highly viscous two part compositions using manual and battery operated applicators without creating unacceptable back pressures, which are easy to use and can be manufactured in a cost effective manner. What are needed are methods for applying viscous two part curable systems utilizing such mixing systems.